The storage temperature is one of the most important factors affecting on the fruit peels composition and quality after harvesting. The pink grapefruit (Citrus paradise L.) peels was subjected in current study to examine the effect of different storage conditions on phytochemical constituents, the antioxidant activity and constants of peels oil. The phytochemical constituents of the pink grapefruit peels such as lycopene, phenolics, flavonoids and vitamin C were assessed the level of their concentrations for examine their antioxidant activities and the effect of storage on those components. The antioxidant effects was determined from the changes in acid value, peroxide number, conjugated diene and triene contents and the delay of rancidity of pink grapefruit peels oil during storage conditions for 60 days in refrigerator temperature at 8 ±1°C and for 40 days in room temperature at 16± 4°C. Results of a proximate composition of pink grapefruit peels during storage conditions showed that significantly decreased (P ≤ 0.05) in moisture, carbohydrate and energy values at most storage periods. On the other side, Protein, fat, fiber and ash contents were significantly increased (P ≤ 0.05) in most different storage periods. The Antioxidants components such as:  Lycopene, total phenolics, and total flavonoids content; as well as, antioxidant activity of pink grapefruit peels were significantly increased (P ≤ 0.05) during storage conditions, while, ascorbic acid levels were significantly (P ≤ 0.05) decreased during storage periods at different storage conditions. The rates of increase in antioxidant activity of samples stored at room temperature were higher than in the refrigerator. The contents of peroxide number, conjugated diene and triene was significantly (p ≤ 0.05) increased for most storage periods at room temperature (16± 4°C), while, non-significant differences (p ≤ 0.05) were found during storage periods at refrigerator temperature (8 ±1°C). On the other hand, acid value was significantly decreased (p ≤ 0.05) after 20 days of storage at room temperature, while, non-significant differences (p ≤ 0.05) were found during storage periods at refrigerator temperature. The storage at refrigerator temperature (8 ±1°C) improved the shelf-life of pink grapefruit peels and to maintain health promoting compounds.

Key words: Grapefruit peels, Bioactive compounds, Antioxidant activity, Storage conditions, Peels oil properties.